U.S. patent number 4,500,416 [Application Number 06/562,993] was granted by the patent office on 1985-02-19 for process for the preparation of hydrocarbon oil distillates.
This patent grant is currently assigned to Shell Oil Company. Invention is credited to Willem H. J. Stork, Robert H. van Dongen.
United States Patent |
4,500,416 |
van Dongen , et al. |
February 19, 1985 |
Process for the preparation of hydrocarbon oil distillates
Abstract
Distillates are prepared from asphaltenes-rich feeds by a
process comprising subjecting the feed to solvent deasphalting, and
subjecting the resulting asphaltic bitumen fraction to a
combination of catalytic hydrotreating and thermal cracking.
Inventors: |
van Dongen; Robert H.
(Amsterdam, NL), Stork; Willem H. J. (Amsterdam,
NL) |
Assignee: |
Shell Oil Company (Houston,
TX)
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Family
ID: |
19838558 |
Appl.
No.: |
06/562,993 |
Filed: |
December 16, 1983 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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420556 |
Sep 20, 1982 |
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Foreign Application Priority Data
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Dec 16, 1981 [NL] |
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8105660 |
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Current U.S.
Class: |
208/86; 208/61;
208/89 |
Current CPC
Class: |
C10G
67/0463 (20130101); C10G 2300/107 (20130101) |
Current International
Class: |
C10G
69/06 (20060101); C10G 67/00 (20060101); C10G
67/04 (20060101); C10G 69/00 (20060101); C10G
067/04 (); C10G 069/06 () |
Field of
Search: |
;208/80,86,57,61,89 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1546960 |
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May 1979 |
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GB |
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2093477 |
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Sep 1982 |
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GB |
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Primary Examiner: Gantz; Delbert E.
Assistant Examiner: Chaudhuri; O.
Parent Case Text
This is continuation, of application Ser. No. 420,556, filed Sept.
20, 1982 now abandoned.
Claims
What is claimed is:
1. A process for the production of hydrocarbon oil distillates from
a hydrocarbon mixture feed stream containing asphaltenes, said
process comprising
(a) solvent deasphalting said feed stream in a deasphalting zone to
obtain a deasphalted oil fraction and an asphaltic bitumen
fraction;
(b) catalytically hydrotreating said asphaltic bitumen fraction in
a hydrotreating zone, therein producing a first product stream
having a reduced asphaltenes content;
(c) fractionating said first product stream into one or more light
distillate fractions and a first heavy distillate fraction;
(d) thermally cracking said first heavy distillate fraction and
said deasphalted oil fraction in a thermal cracking zone into a
second product stream containing less than 20 percent by weight
C.sub.4 to C.sub.1 hydrocarbons;
(e) fractionating said second product stream into one or more light
distillate fractions and a second heavy distillate fraction;
and
(f) routing said second heavy distillate fraction to said
hydrotreating zone wherein said second heavy distillate fraction is
catalytically hydrotreated.
2. A process for the production of hydrocarbon oil distillates from
a hydrocarbon mixture feed stream containing asphaltenes, said
process comprising
(a) solvent deasphalting said feed stream in a deasphalting zone to
obtain a deasphalted oil fraction and an asphaltic bitumen
fraction;
(b) catalytically hydrotreating said asphaltic bitumen fraction in
a hydrotreating zone, therein producing a first product stream
having a reduced asphaltenes content;
(c) fractionating said first product stream into one or more light
distillate fractions and a first heavy distillate fraction;
(d) routing said first heavy distillate fraction to said
deasphalting zone wherein said first heavy distillate fraction is
solvent deasphalted;
(e) thermally cracking said deasphalted oil fraction in a thermal
cracking zone into a second product stream containing less than 20
percent by weight C.sub.4 to C.sub.1 hydrocarbons;
(f) fractionating said second product stream into one or more light
distillate fractions and a second heavy distillate fraction;
and
(g) routing said second heavy distillate fraction to said
hydrotreating zone wherein said second heavy distillate fraction is
catalytically hydrotreated.
3. The process according to claims 1 or 2 wherein said feed stream
is a hydrocarbon mixture which boils substantially above
350.degree. C., more than 35 percent by weight of which boils above
520.degree. C., and which has an RCT of more than 7.5 percent by
weight.
4. The process according to claims 1 or 2 wherein said feed stream
is a residue obtained in the vacuum distillation of an atmospheric
distillation residue from a crude mineral oil.
5. The process according to claims 1 or 2 wherein said catalytic
hydrotreating comprises contacting said asphaltic bitumen fraction
with a catalyst comprising at least one metal selected from the
group consisting of nickel, cobalt and mixtures thereof and in
addition, at least one metal selected from the group consisting of
molybdenum, tungsten and mixtures thereof, deposited on a carrier,
which carrier comprises more than 40% by weight alumina.
6. The process according to claim 5 wherein said catalyst is
selected from the group consisting of nickel/molybdenum on alumina
and cobalt/molybdenum on alumina.
7. The process according to claims 1 or 2 wherein said catalytic
hydrotreatment is carried out at a temperature of from 350.degree.
to 450.degree. C., a pressure of from 75 to 200 bar, a space
velocity of from 0.1 to 2 g.g.sup.-1.hour.sup.-1 and a H.sub.2
/feed ratio of from 500 to 2000 Nl.kg.sup.-1.
8. The process according to claims 1 or 2 wherein said solvent
deasphalting is carried out using n-butane as the solvent at a
pressure of from 35 to 45 bar and a temperature of from 100.degree.
to 150.degree. C.
9. The process according to claims 1 or 2 wherein said thermal
cracking is carried out at a temperature of from 400.degree. to
525.degree. C. and a space velocity of from 0.01 to 5 kg feed per
liter of cracking reactor volume per minute.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for the preparation of
hydrocarbon oil distillates from asphaltenes-containing hydrocarbon
mixtures.
2. Description of the Prior Art
In the atmospheric distillation of crude mineral oil for the
preparation of light hydrocarbon oil distillates, such as gasoline,
kerosene and gas oil, an asphaltenes-containing residue is formed
as a by-product. In the beginning these atmospheric residues (which
in addition to asphlatenes, usually contain a considerable
percentage of sulfur and metals) were used as fuel oil. In view of
the growing demand for light hydrocarbon oil distillates and the
shrinking reserves of crude mineral oil, various treatments have
already been proposed which aimed at converting atmospheric
residues into light hydrocarbon oil distillates. For instance, the
atmospheric residue may be subjected to thermal cracking. Further,
the atmospheric residue may be separated by vacuum distillation
into a vacuum distillate and a vacuum residue, the vacuum
distillate may be subjected to thermal cracking or to catalytic
cracking in the presence or in the absence of hydrogen and the
vacuum residue to thermal cracking. Finally, the vacuum residue may
be separated by solvent deasphalting into a deasphalted oil and an
asphaltic bitumen, the deasphalted oil may be subjected to thermal
cracking or to catalytic cracking in the presence or in the absence
of hydrogen, and the asphaltic bitumen to thermal cracking. One
such process to prepare light hydrocarbon distillates is disclosed
in U.S. Pat. No. 4,039,429. However, these prior art processes
still have ample room for improvement.
SUMMARY OF THE INVENTION
Thermal cracking (TC) refers to the process wherein a heavy
feedstock is converted into a product which contains less than 20%w
C.sub.4.sup.- (C.sub.4 to C.sub.1 hydrocarbons and from which one
or more distillate fractions may be separated as the desired light
product and a heavy fraction as a by-product. Thermal cracking has
proved in actual practice to be a suitable treatment for the
preparation of hydrocarbon oil distillates from a variety of
asphaltenes-containing hydrocarbon mixtures. In the present
invention we have investigated whether combining the TC treatment
with pretreatment of the heavy feedstock and/or aftertreatment of
the heavy fraction separated from the product of thermal cracking,
and using at least part of the aftertreated heavy fraction as feed
for the TC treatment, might yield a better result than employing
nothing but the TC. In the assessment of the results the yield of
light product is most important. Next, the qualities of the light
and heavy product are of importance. In this context the quality of
the light product is taken to be its suitability for processing
into a valuable light fuel oil. This suitability will be greater
according as the light product has, among other things, lower
sulfur and olefin contents. In this context the quality of the
heavy product is taken to be its suitability for use as a fuel oil
component. This suitability will be greater according as the heavy
product has among other things, lower metal and sulfur contents and
lower viscosity and density. As pretreatments for the feed of the
TC treatment and as aftertreatments for the heavy fraction of the
TC product the following treatments were investigated: solvent
deasphalting (DA) in which an asphaltenes-containing feed is
converted into a product from which a deasphalted oil fraction and
an asphaltic bitumen fraction are separated, and catalytic
hydrotreatment (HT) in which an asphaltenes-containing feed is
converted into a product having a reduced asphaltenes content from
which can be separated one or more distillate fractions as the
desired light product and a heavy fraction.
During the investigation a comparison was made between the results
which can be obtained when equal quantities of an
asphaltenes-containing hydrocarbon mixture are used as the starting
material in the preparation of a hydrocarbon oil distillate having
a given boiling range and a heavy by-product by using
(a) nothing but TC,
(b) TC combined with DA,
(c) TC combined with HT, and
(d) TC combined with both DA and HT,
the conditions of the various treatments being as similar as
possible. In view of the quantity and quality of the hydrocarbon
oil distillate and the quality of the heavy by-product to be
obtained in each of the procedures, the various procedures may be
arranged as follows:
______________________________________ Quantity of hydrocarbon oil
distillate d > c > b > a Quality of hydrocarbon oil
distillate c > d > a > b Quality of heavy by-product c
> d > a > b ______________________________________
Taking into account the considerable difference in yield of
hydrocarbon oil distillate obtained using procedures (c) and (d)
and the no more than slight differences between the qualities of
the hydrocarbon oil distillates and the heavy by-products obtained
using procedures (c) and (d), a procedure in which a combination of
a TC treatment, a DA treatment and a HT is used is much
preferred.
As regards the order in which the three treatments are carried out
and also the feeds used for each of the three treatments, a number
of embodiments may be considered. In all the embodiments the
deasphalted oil fraction which is separated from the product of the
DA treatment is used as the feed or a feed component for the TC
treatment. Each of the embodiments may be placed in one of the
following three classes:
I. First, the asphaltenes-containing feed is subjected to a HT,
from the product thus formed a heavy fraction is separated and
subjected to a combination of a DA treatment and a TC
treatment.
II. First, the asphaltenes-containing feed is subjected to a DA
treatment, from the product thus obtained a deasphalted oil
fraction and an asphaltic bitumen fraction are separated and these
are both subjected to a combination of a TC treatment and a HT.
III. First, the asphaltenes-containing feed is subjected to a TC
treatment, from the product thus obtained a heavy fraction is
separated and subjected to a combination of a HT and a DA
treatment.
The embodiments belonging to class II form the subject matter of
the present patent application. The embodiments belonging to
classes I and III form the subject matter of U.S. Pat. No.
4,405,441, and U.S. Pat. No. 4,400,264, respectively, both patents
having a common assignee.
The embodiments to which the present patent application relates may
further be subdivided depending on whether the asphaltic bitumen
fraction is used either as the feed or a feed component for the HT
(class IIA), as a feed component for the HT with the heavy fraction
from the HT being used as a feed component for the DA treatment
(class IIB), or as a feed component for the TC treatment (class
IIC). In the embodiments belonging to class IIA the heavy fraction
from the HT is used as a feed component for the TC treatment. In
the embodiment belonging to class IIB the heavy fraction from the
TC treatment is used as a feed component for the HT. In the
embodiments belonging to class IIC the heavy fraction from the TC
treatment is used as the feed for the HT and the heavy fraction
from the HT is used as a feed component for the DA treatment and/or
as a feed component for the TC treatment.
The present patent application therefore relates to a process for
the preparation of hydrocarbon oil distillates from
asphaltenes-containing hydrocarbon mixtures, in which an
asphaltenes-containing hydrocarbon mixture (stream 1) is subjected
to a DA treatment in which an asphaltenes-containing feed is
converted into a product from which a deasphalted oil fraction
(stream 3) and an asphaltic bitumen fraction (stream 4) are
separated, in which stream 3 and stream 4 are subjected to a
combination of the following two treatments: a HT in which an
asphaltenes-containing feed is converted into a product having a
reduced asphaltenes content from which one or more distillate
fractions and a heavy fraction (stream 2) are separated and a TC
treatment in which one feed or two individual feeds are converted
into a product which comprises less than 20%w C.sub.4.sup.-
hydrocarbons and from which one or more distillate fractions and a
heavy fraction (stream 5) are separated, in which stream 3 is used
as feed or feed component for the TC treatment and in which stream
4 is used either
(1) as the feed or a feed component for the HT with stream 2 being
used as a feed component for the TC treatment, or
(2) as a feed component for the HT with stream 2 being used as a
feed component for the DA treatment and stream 5 as a feed
component for the HT, or
(3) as a feed component for the TC treatment with stream 5 being
used as the feed for the HT and stream 2 as a feed component for
the DA treatment and/or as a feed component for the TC
treatment.
In a particular embodiment, the present invention relates to a
process for the production of hydrocarbon oil distillates from a
hydrocarbon mixture feed stream containing asphaltenes, said
process comprising:
(a) solvent deasphalting said feed stream in a deasphalting zone to
obtain a deasphalted oil fraction and an asphaltic bitumen
fraction;
(b) catalytically hydrotreating said asphaltic bitumen fraction in
a hydrotreating zone, therein producing a first product stream
having a reduced asphaltenes content;
(c) fractionating said first product stream into one or more light
distillate fractions and a first heavy distillate fraction;
(d) thermally cracking said first heavy distillate fraction and
said deasphalted oil fraction in a thermal cracking zone into a
second product stream containing less than 20 percent by weight
C.sub.4 to C.sub.1 hydrocarbons;
(e) fractionating said second product stream into one or more light
distillate fractions and a second heavy distillate fraction;
and
(f) routing said second heavy distillate fraction to said
hydrotreating zone wherein said second heavy distillate fraction is
catalytically hydrotreated.
In an alternative embodiment, the present invention relates to a
process for the production of hydrocarbon oil distillates from a
hydrocarbon mixture feed stream containing asphaltenes, said
process comprising:
(a) solvent deasphalting said feed stream in a deasphalting zone to
obtain a deasphalted oil fraction and an asphaltic bitumen
fraction;
(b) catalytically hydrotreating said asphaltic bitumen fraction in
a hydrotreating zone, therein producing a first product stream
having a reduced asphaltenes content;
(c) fractionating said first product stream into one or more light
distillate fractions and a first heavy distillate fraction;
(d) routing said first heavy distillate fraction to said
deasphalting zone wherein said first heavy distillate fraction is
solvent deasphalted;
(e) thermally cracking said deasphalted oil fraction in a thermal
cracking zone into a second product stream containing less than 20
percent by weight C.sub.4 to C.sub.1 hydrocarbons;
(f) fractionating said second product stream into one or more light
distillate fractions and a second heavy distillate fraction;
and
(g) routing said second heavy distillate fraction to said
hydrotreating zone wherein said second heavy distillate fraction is
catalytically hydrotreated.
BRIEF DESCRIPTION OF THE DRAWING
FIGS. 1-6 each illustrate different embodiments of the processing
scheme according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
In the process according to the invention the feed used is an
asphaltenes-containing hydrocarbon mixture. A suitable parameter
for the assessment of the asphaltenes content of a hydrocarbon
mixture as well as of the reduction of the asphaltenes content
which appears when an asphaltenes-containing hydrocarbon mixture is
subjected to a HT, is the Ramsbottom Carbon Test value (RCT). The
higher the asphaltenes content of the hydrocarbon mixture, the
higher the RCT. Preferably, the process is applied to hydrocarbon
mixtures which boil substantially above 350.degree. C. and more
than 35%w of which boils above 520.degree. C. and which have an RCT
of aore than 7.5%w. Examples of such hydrocarbon mixtures are
residues obtained in the distillation of crude mineral oils and
also heavy hydrocarbon mixtures obtained from shale and tar sand.
If required, the process may also be applied to heavy crude mineral
oils, residues obtained in the distillation of products formed in
the thermal cracking of hydrocarbon mixtures and asphaltic bitumen
obtained in the solvent deasphalting of asphaltenes-containing
hydrocarbon mixtures. The process according to the invention can
very suitably be applied to residues obtained in the vacuum
distillation of atmospheric distillation residues from crude
mineral oils. If an atmospheric distillation residue from a crude
mineral oil is available as feed for the process according to the
invention, it is preferred to separate a vacuum distillate
therefrom by vacuum distillation and to subject the resulting
vacuum residue to the DA treatment. The separated vacuum distillate
may be subjected to thermal cracking or to catalytic cracking in
the presence or in the absence of hydrogen to convert it into light
hydrocarbon oil distillates. The separated vacuum distillate is
very suitable for use as a feed component for the TC treatment,
together with stream 3.
The process according to the invention is a three-step process in
which in the first step an asphaltenes-containing feed (stream 1)
is subjected to a DA treatment for the preparation of a product
from which a deasphalted oil fraction (stream 3) and an asphaltic
bitumen fraction (stream 4) are separated. In the second and third
steps of the process stream 3 and stream 4 are subjected to a
combination of a TC treatment and a HT. Suitable solvents for
carrying out the DA treatment are paraffinic hydrocarbons having of
from 3-6 hydrocarbon atoms per molecule, such as n-butane and
mixtures thereof, such as mixtures of propane and n-butane and
mixtures of n-butane and n-pentane. Suitable solvent/oil weight
ratios lie between 7:1 and 1:1 and in particular between 4:1 and
1:1. The solvent deasphalting treatment is preferably carried out
at a pressure in the range of from 20 to 100 bar. When n-butane is
used as the solvent, the deasphalting is preferably carried out at
a pressure of from 35-45 bar and a temperature of from
100.degree.-150.degree. C.
In the process according to the invention the second or third step
used is a HT in which an asphaltenes-containing feed is converted
into a product which has a reduced asphaltenes content and from
which one or more distillate fractions and a heavy fraction (stream
2) are separated.
Asphaltenes-containing hydrocarbon mixtures usually include a
considerable percentage of metals particularly vanadium and nickel.
When such hydrocarbon mixtures are subjected to a catalytic
treatment, for instance a HT for the reduction of the asphaltenes
content, as is the case in the process according to the invention,
these metals are deposited on the catalyst used in the HT and thus
shorten its effective life. In view of this asphaltenes-containing
hydrocarbon mixtures having a vanadium + nickel content of more
than 50 ppmw (parts per million by weight) should preferably be
subjected to a demetallization treatment before they are contacted
with the catalyst used in the HT. This demetallization may very
suitably be carried out by contacting the asphaltenes-containing
hydrocarbon mixture, in the presence of hydrogen, with a catalyst
consisting more than 80%w of silica. Both catalysts completely
consisting of silica and catalysts containing one or more metals
having hydrogenating activity--in particular a combination of
nickel and vanadium--emplaced on a carrier substantially consisting
of silica, are suitable for the purpose. When in the process
according to the invention an asphaltenes-containing feed is
subjected to a catalytic demetallization treatment in the presence
of hydrogen, this demetallization may be carried out in a separate
reactor. Since the catalytic demetallization and the HT for the
reduction of the asphaltenes content can be carried out under the
same conditions, the two processes may very suitably be carried out
in the same reactor containing a bed of the demetallization
catalyst and a bed of the catalyst used in the HT,
successively.
Suitable catalysts for carrying out the HT are those containing at
least one metal selected from the group consisting of nickel,
cobalt and mixtures thereof and in addition at least one metal
selected from the group consisting of molybdenum, tungsten and
mixtures thereof on a carrier, which carrier consists more than
40%w of alumina. Catalysts very suitable for use in the HT are
those comprising the metal combinations nickel/molybdenum or
cobalt/molybdenum on alumina as the carrier. The HT is preferably
carried out at a temperature of from 300.degree.-500.degree. C. and
in particular of from 350.degree.-450.degree. C., a pressure of
from 50-300 bar and in particular of from 75-200 bar, a space
velocity of from 0.02-10 g.g.sup.-1.h.sup.-1 particular of from
0.1-2 g.g.sup.-1.h.sup.-1 and a H.sub.2 /feed ratio of from
100-5000 Nl.kg.sup.-1 and in particular of from 500-2000
Nl.kg.sup.-1. As used herein "g" refers to grams, "h" refers to
hours, "Nl" refers to normal liters and "Kg" refers to kilograms.
The conditions used in a catalytic demetallization treatment in the
presence of hydrogen, to be carried out if required, are subject to
the same preference as those for the HT for the reduction of the
asphaltenes content stated hereinbefore.
The HT is preferably carried out in such a way that it yields a
product the C.sub.5.sup.+ fraction of which meets the following
requirements:
(a) the RCT of the C.sub.5.sup.+ fraction amounts to 20-70% of the
feed RCT, and
(b) the difference between the percentages by weight of hydrocarbon
boiling below 350.degree. C. present in the C.sub.5.sup.+ fraction
and in the feed is at most 40.
It should be noted that in the catalytic demetallization, apart
from reduction of the metal content, there will be some reduction
of the RCT and some formation of C.sub.5 -350.degree. C. product. A
similar phenomenon is seen in the HT, in which, apart from
reduction of the RCT and formation of C.sub.5 -350.degree. C.
product, there will be some reduction of the metal content. The
requirements mentioned under (a) and (b) refer to the total RCT
reduction and the total formation of C.sub.5 -350.degree. C.
product (viz. including those occurring in a catalytic
demetallization treatment that may be carried out).
The HT yields a product having a reduced asphaltenes content from
which one or more distillate fractions and a heavy fraction (stream
2) are separated. The distillate fractions separated from the
product may be atmospheric distillates only, but it is preferred to
separate a vacuum distillate from the product as well. This vacuum
distillate may be converted into light hydrocarbon oil distillates
in the ways stated hereinbefore.
In the process according to the invention the second or third step
used is a TC treatment in which one feed or two separate feeds are
converted into a product which contains less than 20%w
C.sub.4.sup.- hydrocarbons and from which one or more distillate
fractions and a heavy fraction (stream 5) are separated. The way in
which the TC treatment is carried out is determined by the quality
of the feeds available for the TC.
If the feed for the TC is composed of nothing but one or more
streams having a relatively low asphaltenes content, such as stream
3--optionally together with one or more vacuum distillates
separated during the process--a TC treatment comprising a single
cracking unit will be sufficient. From the product formed one or
more distillate fractions and a heavy fraction (stream 5) are
separated. The distillate fractions separated from the product may
be atmospheric distillates only, but it is preferred to separate a
vacuum distillate from the product as well. This vacuum distillate
may be converted into light hydrocarbon oil distillates in the ways
stated hereinbefore. If the feed for the TC treatment is composed
of nothing but one or more streams having a relatively low
asphaltenes content, and a TC treatment is used which comprises
only one cracking unit, then a heavy fraction of the cracked
product is preferably recirculated to the cracking unit. For
instance, starting from stream 3 as the feed for the TC treatment a
product may be prepared from which one or more atmospheric
distillates are separated by distillation and subsequently part of
the atmospheric residue may be recirculated to the cracking
unit.
If the feed for the TC treatment is composed of both of one or more
streams having a relatively low asphaltenes content, such as stream
3--optionally together with one or aore vacuum distillates
separated during the process--and of a relatively asphaltenes-rich
stream, such as stream 4 or stream 2 obtained as vacuum residue, it
is preferred to carry out a TC treatment comprising two cracking
units and to crack the two feeds separately to form product from
which one or more distillate fractions and a heavy fraction (stream
5) are separated. The distillate fractions separated from the
products may be atmospheric distillates only, but it is preferred
to separate a vacuum distillate from the products as well. The
separated vacuum distillate may be converted into light hydrocarbon
distillates in the manners described hereinbefore. As is the case
when a TC treatment comprising a single cracking unit is used, so
also when a TC treatment comprising two cracking units is used, a
heavy fraction from the cracked product from the cracking unit in
which the relatively low asphaltenes feed is processed will
preferably be recirculated to that cracking unit. When a TC
treatment comprising two cracking units is used, a relatively low
asphaltenes heavy fraction may, if desired, be separated from the
product obtained in the cracking unit in which the relatively
asphaltenes-rich feed is cracked and be used as a feed component
for the cracking unit in which the relatively low-asphaltenes feed
is processed. When a TC treatment comprising two cracking units is
used, it is not necessary for the distillation of the cracked
products (atmospheric and, optionally, vacuum distillation) to be
carried out in separate distillation units. If desired, the cracked
products or fractions therefrom may be combined and distilled
together.
The TC treatment both of relatively low-asphaltenes feeds and of
relatively asphaltenes-rich feeds should preferably be carried out
at a temperature of from 400.degree.-525.degree. C. and a space
velocity of from 0.01-5 kg fresh feed per liter cracking reactor
volume per minute.
As has been observed hereinbefore, the embodiments to which the
present patent application relates and which fall within class II
may be subdivided depending on whether stream 4 is used either as
the feed or a feed component for the HT (class IIA), or as a feed
component for the HT with stream 2 being used as a feed component
for the DA treatment (class IIB), or as a feed component for the TC
treatment (class IIC). In the embodiments falling within class IIA
stream 2 is used as a feed component for the TC treatment. In the
embodiment falling within class IIB stream 5 is used as a feed
component for the HT. In the embodiments falling within class IIC
stream 5 is used as the feed for the HT and stream 2 as a feed
component for the DA treatment and/or as a feed component for the
TC treatment.
DETAILED DESCRIPTION OF THE DRAWING
The various embodiments falling within class IIA have been
represented schematically in FIG. 1. According to this Figure the
process is carried out in an apparatus comprising a DA zone (106),
a HT zone (107) and a TC zone (108), successively. An
asphaltenes-containing hydrocarbon mixture (101) is subjected to a
DA treatment and the product is separated into a deasphalted oil
(103) and an asphaltic bitumen (104). Stream 4 is subjected to a HT
and the hydrotreated product is separated into one or more
distillate fractions (109) and a residual fraction (102). Streams 2
and 3 are subjected to a TC treatment and the cracked product is
separated into one or more distillate fractions (110) and a
residual fraction (105). Apart from this embodiment (IIA1) in which
stream 5 is not subjected to any further processing, FIG. 1
includes another embodiment (IIA2) in which at least part of stream
5 is used as a feed component for the HT.
The embodiment falling within class IIB has been represented
schematically in FIG. 2. According to the Figure the process is
carried out in an apparatus comprising a DA zone (206), a TC zone
(207) and a HT zone (208), successively. An asphaltenes-containing
hydrocarbon mixture (201) and a residual fraction (202) are
subjected to a DA treatment and the product is separated into a
deasphalted oil (203) and an asphaltic bitumen (204). Stream 3 is
subjected to a TC treatment and the cracked product is separated
into one or more distillate fractions (209) and a residual fraction
(205). Streams 4 and 5 are subjected to a HT and the hydrotreated
product is separated into one or more distillate fractions (210)
and a residual fraction (202).
The various embodiments falling within class IIC are represented
schematically in FIG. 3. According to this Figure the process is
carried out in an apparatus comprising a DA zone (306), a TC zone
(307) and a HT zone (308), successively. An asphaltenes-containing
hydrocarbon mixture (301) is subjected to a DA treatment and the
product is separated into a deasphalted oil (303) and an asphaltic
bitumen (304). Stream 3 and 4 are subjected to a TC treatment and
the cracked product is separated into one or more distillate
fractions (309) and a residual fraction (305). Stream 5 is
subjected to a HT and the hydrotreated product is separated into
one or more distillate fractions (310) and a residual fraction
(302). Stream 2 is used either as a feed component for the DA
treatment (embodiment IIC1), or as a feed component for the TC
treatment (embodiment IIC2), or as a feed component both for the DA
treatment and for the TC treatment (embodiment IIC3).
In the embodiments where it is the object to achieve the most
complete conversion possible of stream (301) into hydrocarbon oil
distillates, a so called "bleed stream" should preferably be
separated from one of the heavy streams of the process. In this way
the build-up of undesirable heavy components during the process can
be obviated.
Three flow diagrams for the preparation of hydrocarbon oil
distillates from asphaltenes-containing hydrocarbon mixtures
according to the invention will hereinafter be explained in more
detail with the aid of FIGS. 4-6.
Flow diagram A (based on embodiment IIA2)
See FIG. 4.
The process is carried out in an apparatus comprising, successively
a DA zone (406), a HT zone composed of a unit for catalytic
hydrotreatment (407), a unit for atmospheric distillation (408) and
a unit for vacuum distillation (409) and a TC zone composed of a
thermal cracking unit (410), a second unit for atmospheric
distillation (411), a second thermal cracking unit (412), a third
unit for atmospheric distillation (413) and a second unit for
vacuum distillation (414). An asphaltenes-containing hydrocarbon
mixture (401) is separated by solvent deasphalting into a
deasphalted oil (403) and an asphaltic bitumen (404). The asphaltic
bitumen (404) is mixed with a vacuum residue (415) and the mixture
(416) is subjected together with hydrogen (417) to a catalytic
hydrotreatment. The hydrotreated product (418) is separated by
atmospheric distillation into a gas fraction (419), an atmospheric
distillate (420) and an atmospheric residue (421). The atmospheric
residue (421) is separated by vacuum distillation into a vacuum
distillate (422) and a vacuum residue (402). The vacuum residue
(402) is subjected to thermal cracking and the cracked product
(423) is separated by atmospheric distillation into a gas fraction
(424), an atmospheric distillate (425) and an atmospheric residue
(426). The deasphalted oil (403) is mixed with an atmospheric
residue (427) and the mixture (428) is subjected to thermal
cracking. The cracked product (429) is separated by atmospheric
distillation into a gas fraction (430), an atmospheric distillate
(431) and an atmospheric residue (432). The atmospheric residue
(432) is divided into two portions (427) and (433). Portion (433)
is mixed with atmospheric residue (426) and the mixture (434) is
separated by vacuum distillation into a vacuum distillate (435) and
a vacuum residue (405). The vacuum residue (405) is divided into
two portions (415) and (436). The gas fractions (424) and (430) are
combined to form the mixture (437) and the atmospheric distillates
(425) and (431) are combined to form mixture (438).
Flow diagram B (based on embodiment IIB)
See FIG. 5.
The process is carried out in an apparatus comprising,
successively, a DA zone (506), a TC zone composed of a thermal
cracking unit (507), a unit for atmospheric distillation (508) and
a unit for vacuum distillation (509) and a HT zone composed of a
unit for catalytic hydrotreatment (510), a second unit for
atmospheric distillation (511) and a second unit for vacuum
distillation (512). An asphaltenes-containing hydrocarbon mixture
(501) is mixed with a vacuum residue (502) and the mixture (513) is
separated by solvent deasphalting into a deasphalted oil (503) and
an asphaltic bitumen (504). The deasphalted oil (503) is mixed with
an atmospheric residue (514) and the mixture (515) is subjected to
thermal cracking. The cracked product (516) is separated by
atmospheric distillation and a stream (518) and an atmospheric
residue (519) are recovered. The atmospheric residue (519) is
divided into two portions (514) and (520) and portion (520) is
separated by vacuum distillation into a vacuum distillate (521) and
a vacuum residue (505). The asphaltic bitumen (504) is divided into
two portions (522) and (523). Portion (522) is mixed with the
vacuum residue (505) and the mixture (524) is subjected together
with hydrogen (525) to a catalytic hydrotreatment. The hydrotreated
product (526) is separated by atmospheric distillation into a gas
fraction (527), an atmospheric distillate (528) and an atmospheric
residue (529). The atmospheric residue (529) is separated by vacuum
distillation into a vacuum distillate (530) and a vacuum residue
(502).
Flow diagram C (based on embodiment IIC1)
See FIG. 6.
The process is carried out in an apparatus comprising,
successively, a DA zone (606), a TC zone composed of a thermal
cracking unit (607), a unit for atmospheric distillation (608), a
second thermal cracking unit (609), a second unit for atmospheric
distillation (610) and a unit for vacuum distillation (611) and a
HT zone composed of a unit for catalytic hydrotreatment (612), a
third unit for atmospheric distillation (613) and a second unit for
vacuum distillation (614). An asphaltenes-containing hydrocarbon
mixture (601) is mixed with a vacuum residue (602) and the mixture
(615) is separated by solvent deasphalting into a deasphalted oil
(603) and an asphaltic bitumen (604). The deasphalted oil (603) is
mixed with an atmospheric residue (616) and the mixture (617) is
converted by thermal cracking into a product (618) which by
atmospheric distillation is separated into a gas fraction (619), an
atmospheric distillate (620) and an atmospheric residue (621). The
atmospheric residue (621) is divided into two portions (616) and
(622). The asphaltic bitumen (604) is converted by thermal cracking
into a product (623) which by atmospheric distillation is separated
into a gas fraction (624), an atmospheric distillate (625) and an
atmospheric residue (626). The gas fractions (619) and (624) are
combined to form the mixture (627) and the atmospheric distillates
(620) and (625) are combined to form the mixture (628). The
atmospheric residues (622) and (626) are combined and the mixture
(629) is separated by vacuum distillation into a vacuum distillate
(630) and a vacuum residue (605). The vacuum residue (605) is
divided into two portions (631) and (632). The vacuum residue (632)
is subjected together with hydrogen (633) to a catalytic
hydrotreatment. The hydrotreated product (634) is separated by
atmospheric distillation into a gas fraction (635), an atmospheric
distillate (636) and an atmospheric residue (637). The atmospheric
residue (637) is separated by vacuum distillation into a vacuum
distillate (638) and a vacuum residue (602).
The present patent application also includes apparatuses for
carrying out the process according to the invention substantially
corresponding with those schematically represented in FIGS.
1-6.
The invention is now illustrated with the aid of the following
examples, which are given for illustration only and are not meant
to limit the invention to the particular reactants and conditions
employed therein.
The starting mixtures used in the process according to the
invention were three asphaltenes-containing hydrocarbon mixtures
obtained as residues in the vacuum distillation of atmospheric
distillation residues from crude mineral oils from the Middle East.
All three vacuum residues boiled substantially above 520.degree.
C.; they had RCT's of 21.0, 18.1 and 14.8%w, respectively. The
process was carried out according to flow diagrams A-C. The
following conditions were used in the various zones:
In all the flow diagrams the unit for catalytic hydrotreatment
comprised two reactors, the first of which was filled with a
Ni/V/SiO.sub.2 catalyst containing 0.5 pbw (parts by weight) of
nickel and 2.0 pbw of vanadium per 100 pbw of silica, and the
second of which was filled with a Co/Mo/Al.sub.2 O.sub.3 catalyst
containing 4 pbw of cobalt and 12 pbw of molybdenum per 100 pbw of
alumina. The catalytic hydrotreatment was carried out at a hydrogen
pressure of 150 bar and a H.sub.2 /feed ratio of 1000 Nl per
kg.
In all the flow diagrams the DA treatment was carried out at a
pressure of 40 bar using n-butane as solvent.
In all the flow diagrams the TC treatment was carried out in one or
two cracking coils at a pressure of 20 bar and a space velocity of
0.4 kg fresh feed per liter cracking coil volume per minute.
Further information concerning the conditions under which the HT,
the DA treatment and the TC treatment were carried out is given in
the Table.
TABLE ______________________________________ Example 1 2 3
______________________________________ Carried out according to A B
C flow diagram Flow diagram represented 4 5 6 in Figure HT Space
velocity measured for 0.2 0.2 0.3 both reactors, kg.
1..sup.-1.h.sup.-1 Average temperature in 410 410 410 first
reactor, .degree.C. Average temperature in 400 400 395 second
reactor, .degree.C. DA Solvent/oil weight ratio 2:1 3:1 2:1
Temperature, .degree.C. 120 120 125 TC Number of cracking units 2 1
2 Temperature in first cracking 495 -- 480 unit, .degree.C.*
Temperature in second cracking 485 490 490 unit, .degree.C.*
Recirculation ratio in second 2 3 2 cracking unit (% w residue per
% w fresh feed) ______________________________________ *The
cracking temperatures given were measured at the outlet of the
cracking coils.
EXAMPLE 1
100 pbw 520.degree. C..sup.+ residue (401) having an RCT of 21.0%w
yielded the various streams in the following quantities:
56.0 pbw deasphalted oil (403),
4.0 pbw asphaltic bitumen (404),
72.6 pbw mixture (416) having an RCT of 37.5%w,
a product (418) the C.sub.5.sup.+ fraction of which had an RCT of
12.5%w,
14.8 pbw C.sub.5 -350.degree. C. atmospheric distillate (420),
52.3 pbw 350.degree. C..sup.+ atmospheric residue (421),
22.5 pbw 350.degree.-520.degree. C. vacuum distillate (422),
29.8 pbw 520.degree. C..sup.+ vacuum residue (402),
24.2 pbw C.sub.5 -350.degree. C. atmospheric distillate (438),
57.6 pbw 350.degree. C..sup.+ atmospheric residue (434),
18.0 pbw 350.degree.-520.degree. C. vacuum distillate (435),
39.6 pbw 520.degree. C..sup.+ vacuum residue (405),
28.6 pbw portion (415), and
11.0 pbw portion (436).
EXAMPLE 2
100 pbw 520.degree. C..sup.+ vacuum residue (501) having an RCT of
18.1%w yielded the various streams in the following quantities:
130.2 pbw mixture (513),
72.9 pbw deasphalted oil (503),
57.3 pbw asphaltic bitumen (504),
23.8 pbw C.sub.5 -350.degree. C. atmospheric distillate (518),
45.1 pbw 350.degree. C..sup.+ atmospheric residue (520),
17.4 pbw 350.degree.-520.degree. C. vacuum distillate (521),
27.7 pbw 520.degree. C..sup.+ vacuum residue (505),
44.3 pbw portion (522),
13.0 pbw portion (523),
72.0 pbw mixture (524) having an RCT of 36.6%w,
a product (526) the C.sub.5.sup.+ fraction of which had an RCT of
12.1%w,
14.4 pbw C.sub.5 -350.degree. C. atmospheric distillate (528),
52.4 pbw 350.degree. C..sup.+ atmospheric residue (529),
22.2 pbw 350.degree.-520.degree. C. vacuum distillate (530),
and
30.2 pbw 520.degree. C..sup.+ vacuum residue (502).
EXAMPLE 3
100 pbw 520.degree. C..sup.+ (601) having an RCT of 14.8%w yielded
the various streams in the following quantities:
6.4 pbw mixture (615),
77.1 pbw deasphalted oil (603),
49.3 pbw asphaltic bitumen (604),
35.1 pbw C.sub.5 -350.degree. C. atmospheric distillate (628),
85.5 pbw 350.degree. C..sup.+ atmospheric residue (629),
26.0 pbw 350.degree.-520.degree. C. vacuum distillate (630),
59.5 pbw 520.degree. C..sup.+ residue (605),
8.7 pbw portion (631),
50.8 pbw portion (632) having an RCT of 42.2%w,
a product (634) the C.sub.5 fraction of which had an RCT of
15.9%w,
7.5 pbw C.sub.5 -350.degree. C. atmospheric distillate (636),
40.2 pbw 350.degree. C..sup.+ atmospheric residue (637),
13.8 pbw 350.degree.-520.degree. C. vacuum distillate (638) and
26.4 pbw 520.degree. C..sup.+ vacuum residue (602).
* * * * *